Effect of retinyl acetate on the occurrence of ovarian hormone-responsive and -nonresponsive mammary cancers in the rat.
The inhibitory activity of retinyl acetate against the induction of ovarian hormone-responsive and -nonresponsive mammary gland adenocarcinomas was studied in intact and castrated female Sprague-Dawley rats. Three experiments were conducted. Mammary cancer was induced by a single p.o. administration of 7,12-dimethylbenz(a)anthracene (DMBA) at 50 days of age. Animals in Experiments 1 and 2 each received 20 mg DMBA, whereas those in Experiment 3 received 15 mg. In all experiments, animals were fed a chow diet supplemented per kg with either a placebo or 328 mg retinyl acetate starting 7 days after carcinogen treatment. In Experiment 1, rats were castrated at either 7, 60, or 90 days postcarcinogen and were killed 120 days after DMBA was given. In Experiment 2, rats were castrated 30 days after DMBA and were killed 240 days after carcinogen treatment. In Experiment 3, rats were castrated when a detected tumor attained a measurable diameter, and the hormone responsiveness of their tumors was subsequently determined. The experiment was terminated 279 days after DMBA treatment. In both intact and castrated rats, mammary tumor occurrence was inhibited by treatment with retinyl acetate. However, there were no differences in the latency to appearance time of hormone-responsive and -nonresponsive cancers in intact animals receiving either placebo or retinyl acetate. The data indicate that retinyl acetate inhibits DMBA-induced mammary tumorigenesis in either the presence or the absence of the ovaries. It appears that retinyl acetate is effective in inhibiting both ovarian hormone-responsive and -nonresponsive mammary tumors.
D015127:9,10-Dimethyl-1,2-benzanthracene; D000230:Adenocarcinoma / Q000139:chemically induced / Q000473:pathology; D000818:Animals; D002369:Castration; D004032:Diet; D004224:Diterpenes; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D000084562:Retinyl Esters; D013997:Time Factors; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000494:pharmacology
D004224:Diterpenes; D000084562:Retinyl Esters; D014801:Vitamin A; C009166:retinol acetate; D015127:9,10-Dimethyl-1,2-benzanthracene